Surgical instrument

ABSTRACT

A surgical pencil embodies interfitting relatively rotatable core and cap having eccentrically positioned bores at their forward ends. The two bores are aligned to readily receive and release the shank of a surgical tool when the core and cap are in a first position of relative rotation and are misaligned so as to firmly grasp and insure good electrical contact with the tool shank when the core and cap are in a second position of relative rotation. A resilient cantilevered finger on the core carries a longitudinally extending detent for selective engagement with a number of mating ribs carried by the cap to releasably retain the parts in selected position of relative rotation and to audibly indicate the amount and degree of relative rotation. The instrument is configured to allow one-handed operation to securely lock a tool thereto or to release it so that it will simply drop from the instrument handle.

Pastor Nov. 18, 1975 [54] SURGICAL INSTRUMENT- [76] Inventor: Macey A.Pastor, 62222 Nita Ave.,

' 1 Woodland Hills, Calif. 91364 [22] Filed: Apr. 19, 1974 [21] Appl.No.2 462,383

[52] US. Cl. 128/303.13 [51] Int. Cl. A61B 17/36 [58] Field ofSearch..... 128/303.l3, 303.l4,.303.15, l28/303.16, 303.17, 303.18,303.19; 279/6,

FOREIGN PATENTS OR APPLICATIONS France 403/350 Primary firaminer-channing L. Pace Attorney, Agent, or Firm-Gausewitz, Carr &

. Rothenbe rg [57] ABSTRACT A surgical pencil embodies interfittingrelatively rotatable core and cap having eccentrically positioned boresat their forward ends. The two bores are aligned to readily receive andrelease the shank of a surgical tool when the core and cap are in afirst position of relative rotation and are misaligned so as to firmlygrasp and insure good electrical contact with the tool shank when thecore and cap are in a second position of relative rotation. A resilientcantilevered finger on the core carries a longitudinally extendingdetent for selective engagement with a number of mating ribs carried bythe cap to releasably retain the parts in selected position of relativerotation and to audibly indicate the amount and degree of relativerotation. The instrument is configured to allow one-handed operation tosecurely lock a tool thereto or to release it so that it will simplydrop from the instrument handle.

11 Claims, 9 Drawing Figures US. Patent Nov. 18, 1975 Sheet 2 on3,920,022

SURGICAL INSTRUMENT BACKGROUND OF THE INVENTION 1. Field of theInvention:

The present invention relates to surgical instruments and moreparticularly concerns an instrument handle for holding interchangeabletools.

2. Description of Prior Art In many types of surgical procedures, aslender, elongated blade is employed, often electrically energized.Blades are of many different types and configurations for differentprocedures and further, different blades at times may be employed in asingle operation. For this reason, among others, it is desirable thatthe blades be readily removed and inserted into the instrument handleand, particularly, that they be securely fastened in placed when inuse.

Although sterilization is available for instruments that are repeatedlyused, it is desirable and preferable, if possible, to employ devicesthat are sufficiently simple and inexpensive to permit use in a singleprocedure so that the device may be discarded rather than sterilized forreuse.

Where electrical energization of the instrument blade is employed, it isnecessary that a good electrical contact be made with the blade.Nevertheless, the instrument body and the user must be fully andcompletely insulated from the conductive parts without undue heating.

A number of surgical pencils of the prior art, such as those shown inthe U.S. Pat. Nos. to Peters (3,494,364), Guiorguiev (3,035,580),Wappler (1,717,480 and 1,932,258), Marton (2,110,735), Goode et al(3,597,582), and Miller (3,532,095), employ relatively complex andexpensive instrument bodies, generally too costly to be disposable.Further, these arrangements embody different types of tool-holdingchucks, such as spring-operated devices, which may either hold the toolshank too loosely or too tightly, whereby the tool may be inadvertentlydetached, or may be too difficult to remove when desired. The wet glovesoften worn by a surgeon make it even more difficult to exert a firm pullon the smooth shank of common surgical blades.

Various types of eccentric fastening devices are exemplified by the U.S.Pat. Nos. to Bochory (3,447,820), the patent to Sharp (2,677,813), andthe several patents to Hixon (2,093,079; 2,159,153; 2,182,896; and2,264,754). These eccentric connectors are large and bulky, oftenrequiring a number of different relatively movable parts. Further, theyare not adapted for use with a surgical instrument.

Accordingly, it is an object of the present invention to provide aninstrument of the type described which eliminates or minimizesdisadvantages common in prior artdevices and affords improvements thatallow ready interchangeability of instrument blades in a simple andinexpensive instrument.

SUMMARY OF THE INVENTION body portions so that the tool-receiving boresmay be aligned with each other when the body portions are in a releaseposition of relative rotation and will be relatively misaligned tofirmly grasp the shank of a tool received in both of the bores when thebody portions are relatively rotated to a locked position. Thearrangement is such that the relative rotation may be a onehandedoperation with the operator simply employing his fingers to twist theforward portion relative to the rear portion held in the same hand.According to another feature of the invention, a simplified releasablelocking means is provided to insure a firm gripping of the tool shank.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of asurgical instrument constructed in accordance with the principles of thepresent invention;

FIGS. 2 and 3 are longitudinal sections, with parts broken away, of theinstrument shown in FIG. 1, showing the parts in fastened and releaseposition;

FIG. 4 is a fragmentary perspective view of one end of the core,illustrating the resiliently mounted locking rib;

FIGS. 5 and 6 are sectional view taken on lines 55 and 66 of FIGS. 2 and3, respectively;

FIG. 7 is a section taken on line 7-7 of FIG. 2; and

FIGS. 8 and 9 are sections taken on lines 88 and 99 of FIGS. 5 and 6,respectively.

DETAILED DESCRIPTION As illustrated in FIG. 1, an electrical surgicalpencil releasably holds a tool 10 having a blade 12 and a substantiallycylindrical shank 14. The pencil comprises a forward body portion or cap16 and a rear body assembly 18 which is mounted to the forward bodyportion 16 for rotation relative thereto about an axis substantiallyaligned with the longitudinal center line of the pencil.

The forward body portion 16 comprises a slender elongated outer tubularelement 20 having a first tool receiving bore 22 formed in the front endthereof and extending inwardly from the front tip 24 of the outertubular sleeve 20.- At a suitable distance from the front end, adistance of approximately one half inch, for example, the tool receivingbore 22 terminates and communicates with an inner enlarged bore 26 whichextends rearwardly throughout the remaining length of the outer tubularelement to the rear end 28 thereof.

The rear body assembly 18 is formed of a core or inner tubular element30 and a rear sleeve 32 which is secured thereto to provide a suitablerearward extension of the inner tubular element 30. Element 30 has afront end 34 which is formed with a cylindrical outer surface that isrotatably received within the inner enlarged bore 26 of element 20. Theouter peripheral surface of the inner tubular element 30, at therearward end thereof as indicated at 36, also has a substantiallycylindrical surface (except for certain ribs formed therein as will bemore particularly described hereinafter) which rotatably rides withinthe inner cylindrical surface of the rearward end of the element 20.Accordingly, the inner tubular element 30, together with its fixedrearward extension 32, is firmly and smoothly rotatably mounted to andwithin the outer tubular element 20.

Inner element 30 is also formed with a tool receiving bore 38a extendingfrom the front end therein, which bore is defined by a metallic sleeve38 having a flanged front end 40. Flange 40 is captured between thefront end of the inner tubular element 30 and the shoulder 42 formed bythe stepped transition from the tool receiving bore 22 to the enlargedinner bore 26 of the cap 20.

Sleeve 38 receives and is crimped upon a bared end 44 of an insulatedelectrical conductor 46 that extends through the hollow body of core 30and through the hollow body of the rear extension 32 for connection to asuitable source of electrical energy (not shown).

Cap 20 has a plurality of circumferentially spaced longitudinallyextending grooves 51 formed in its outer surface to facilitate grippingby the fingers of the user. If desired, rear extension 32 may besimilarly formed with longitudinally extending grooves to facilitategripping thereof. Conveniently the outer tubular element or cap 16 ismade identical in size and shape to the rear extension 32 except for theformation of certain resilient locking ribs and a circumferentiallyextending slot, more particularly described below, that is formed in thecap 20.

The enlarged inner bore 26 of cap 20 is centered on an axissubstantially aligned with the longitudinal axis of the entireinstrument. The cylindrical outer surface of the front end 34 of core 30is centered upon an axis coaxial with the axis of the surface of bore26, so that relative rotation of the cap 20 and core 30 occur about asingle axis of rotation. However, for the purpose of providing a chuckto insure rapid and positive gripping of the tool shank 14, when thelatter is inserted into the tool receiving bores 22 and 38a, the bores22 and 38a are centered upon an axis that is displaced from the axis ofrelative rotation of the cap and core. Bores 22 and 380 are positionedso that in one position or condition of relative rotation of the cap 20and core 30, the two bores are mutually aligned. This position ofalignment is illustrated in FIG. 3 and the sections thereof shown inFIGS. 6 and 9. With this mutual alignment of the two tool-receivingbores 22 and 38a, the tool shank I4 is relatively loosely received inboth of the bores since the bores are formed with substantially mutuallyequal diameters that are slightly larger than, or at least will providea relatively loose fit for, a tool shank of maximum diameter within thetolerance allowed in the tool manufacture. This arrangement allows theinstrument to be used with tools of relatively widely varying tolerance.Thus, in this unlocked or aligned position, illustrated in FIGS. 3, 6and 9, the tool shank is readily received within the two bores 22 and38a and, further, may be readily removed therefrom, for example, simplyby pointing the tool receiving end of the instrument downwardly andallowing the tool to drop by virtue of its own weight.

Relative rotation of the cap 20 and core 30 through a relatively smallangle, on the order of 90 or less, moves the parts to a locked positionillustrated in FIGS. 2, and 8. In this locked position, the relativerotation of the core and cap has moved the two bores 22 and 38a topositions of mutual misalignment, the position of bore 38a beingindicated in the dotted lines in FIG. 5 and the position of bore 22being indicated in solid lines in FIG. 5. In this position of relativemisalignment, the tool shank 14 is tightly grasped by the tool receivingbores and pressed firmly into contact with and over a relatively largearea of the electrically conductive sleeve 38 which defines the bore38a. This contact insures not only a secure locking of the tool shankwithin 4 the instrument handle, but also insures a good electricalcontact with the shank of the metallic tool.

As best illustrated in FIG. 7, the rear end portion 50 of the cap 20 isformed with a plurality of ribs 52a, b, 0, etc., which project radiallyinwardly therefrom and collectively define radially inwardly facinggrooves 54a, b, c, etc., therebetween. Near the rear end 36 of the core30 (as best seen in FIG. 4) there is provided a cantilevered resilientfinger 56 which is conveniently formed from the body of the core 30 bymeans of a substantially U-shaped slot 58 cut through the core body.Formed upon the free or cantilevered end of the spring finger 56 is aradially outwardly projecting detent or rib 60 which has a longitudinalextent substantially equal to the longitudinal extend of the ribs 52a,b, c, etc. Also formed upon the spring finger and projecting radiallyoutwardly therefrom, just forward of the rib 60, is a lug 62 thatprojects into a circumferentially extending slot 64 fonned in the rearend portion of the core just forward of the ribs 52 a, b, c, etc.

The resiliently mounted rib 60 cooperates with the ribs 52a, 52b, 52c,to form releasable locking or latching means that will restrain relativerotation of the cap and core, and which yet may be readily released bydepressing the lug 62 a distance sufficient to at least partiallydisengage rib 60 from one of the grooves 54a, 54b, 54c, and thus permitrelative rotation of the parts. Preferably, a visual indicator such asgroove 65 provided with a suitably contrasting color or stripe, isformed on the lug 62 for cooperation with other indicia such as theprinted word Lock, for example (not shown), that may be affixed to therear end portion 50 of the cap 20. These indicia afford a visualindication of the position or condition of the pencil indicating whetherit is in locked (gripping) or unlocked (release) position. Further, thelocking rib 60 will provide a series of audible clicks and discretetactile sensations as the rib 60 rides over successive ones of the ribs52a, b, c, etc., during relative rotation. Thus, there is provided acombination of visual, audible and tactile indications of the locked orunlocked condition of the instrument which greatly facilitates properpositioning to insure locked condition of the surgical tool and also beprovide a psychological assurance to the user.

It will be readily appreciated that the described instrument may be madeof many of many different types of material and by many differentmanufacturing techniques. Nevertheless, for those situations wheresimplicity, cost and rapidity of manufacture are desirable goals, as foruse in a disposable instrument for example, the parts are preferablyinjection molded of a suitable electrically non-conductive plastic suchas Delrin or Lexan for example. As previously indicated, the cap 20 andthe rear extension 32 of the core assembly 18 are made substantiallyindentical except for the slot 64 and ribs 52 formed in the cap. Core 30is alsoinjection molded, including the resilient finger 56, rib 60 andlug 62 thereof. Further, core 30 is formed with a radially outwardlyprojecting circumferential stop 58 to facilitate precise positioning ofthe rear extension 32.

The instrument parts are readily assembled by sliding the rear extension32 up on the core 30 into firm abuttment with stop 58. These parts maybe suitably bonded to each other as by adhesive or sonci welding forexample. Then the end 44 of conductor 46 is crimped into the end ofsleeve 38 and threaded through body of the core 30 until the flange 40of the sleeve 48 bears against the forward end of the front portion 34of the core. It may be noted that the sleeve '38 is a relatively loosefit within the core 34 since it will be retained in place by thecaptureof its flange 40 between the front end of the core 34 and theshoulder 42 of cap 20. Now the lug 62 is depressed to move the springfinger 56 radially inwardly and allow the inner surface of the rear endof cap to be slid over the'front end of the core 30 until the lug 62isregistered with slot 64. The lug is released and the two parts are thenlocked againstrelative axial motion, although the slot 64 and lug 62allow the required amount of relative rotation. Assembly is nowcompleted and the; instrument is ready for use. It will be seen that theentire apparatus is readily and inexpensively made, particularly sincelittle precision is required and tolerances may be relatively large.Resilience of the rearwardly extendingportions of the core 30 where theyrotatably engage the inner surfaces of the rear portions of cap 20allows significant tolerances in dimensions of these parts. Further,relatively large tolerances may be employed in the dimensions of themetallic sleeve 38 and the bore formed in front end 34 of core 30because of the nature of the locking operation of eccentric toolreceiving bores. Still further, the eccentric bores allow use of toolshanks with relatively large tolerances since locking upon a tool shankof somewhat smaller than nominal diameter requires only a slightlygreater amount of relative angular rotation. Locking upon a tool shankof somewhat larger than nominal diameter requires a lesser amount ofrelative rotation of the core and cap. A wide range of blade shapes andtypes may be employed whether or not electrically energized, includingloops, needles and various types of cutting configurations.

The locking and unlocking of a tool shank is readily performed by onehand. For example, the rear body portion or core 30 together with itsrear extension 32 may be grasped between the palm of the hand and thefourth and fifth fingers, while the thumb and forefinger grasp theforward body portion or cap 20 to achieve a simple and positive relativerotation between locked and unlocked positions.

In an exemplary embodiment, the entire instrument, without a blade, mayhave a length of between six and seven inches and an overall outerdiamter of a quarter to three-eighths of an inch. Enlarged inner bore 26may have a diameter of approximately one-quarter inch, with .the wallthickness of the cap at the enlarged bore being about one-sixteenth ofan inch. Tool shank receiving bores 22 and 38a mayhave a diameter,depending upon the nominal size of a tool shank, which is in the orderof one-eighth inches. Offset of the axis upon which the tool receivingbores are centered with respect to the axis of relative rotation is0.008 inches in this exemplary embodiment, and the circumferentialextent of the slot 64 is slightly more than 90 whereby a relativerotationof approximately 90 is available. It will be readily understoodthat the described dimensions are illustrative only since principles ofthe invention may be applied to a number of different configurations andsizes of devices made by other and different manufacturing techniques.

There has been described an improved, disposable, electrosurgical pencilformed of few and inexpensively made parts, providing simple and secureoperation for one-handed release and locking of interchangeableinstrument tools. r

The foregoing detailed description is to be clearly understood as givenby way of illustration and example only, the spirit and scope of thisinvention being limited solely by the appended claims. What is claimedis:

1. A surgical instrument comprising a rear body por- 5 tion adapted tobe held in the hand of an operator,

a forward body portion mounted to said rear body portion for rotationabout a first axis and adapted to be grasped and rotated by the fingersof the hand in which the rear body portion is held,

said body portions respectively having first and second tool receivingbores positioned atrespective forward ends thereof and of substantiallyequal diameters, each said bore centered upon an axis displaced fromsaid first axis,

said bores being aligned with each other when said body portions are ina first release position of relative angular rotation about said firstaxis, and being relatively misaligned when said body portions are in asecond gripping position of relative angular rotation, whereby a toolshank may be freely inserted into or withdrawn from said aligned boreswhen the body portions are in said release position and said tool shankwill be firmly grasped by the relatively misaligned bores when the bodyportions are in said gripping postion, said body portions being readilydisplaced between said gripping and release positions by a one-handedoperation in which said forward body portion may be grasped between theoperators thumb and another finger and said rear body portion may begrasped between the operators palm and other f'mgers of the same hand toaccomplish movement of the body portions between said gripping andrelease positions, said forward body portion comprising an outerelongated tubular element having said first tool receiving bore formedin a front end thereof and having an enlarged inner bore extending froman inner end of said first tool receiving bore to the rearward end ofsaid tubular element, said rear body portion comprising an inner tubularelement having a front end portion rotatably received in a forwardportion of said enlarged inner bore of said outer tubular element toprovide at least part of the rotatable mounting of said body portions,said tool receiving bore of said rear body portion extending throughsaid front end portion of said inner tubular element in end-to-endrelation to the tool receiving bore of said outer tubular element,

said inner tubular element including an outer peripheral surfacerotatably engaged with an inner surface of the inner bore of said firsttubular element at a rear end thereof to provide a part of the rotatablemounting of the two body portions,

inner tubular element being axially inserted into said first tubularelement and including means for restraining relative rotation of saidtubular elements in any one of a plurality of positions of relativerotation.

2. The instrument of claim 1 wherein said means for limiting relativerotationcomprises a circumferentially extending slot formed in saidouter tubular element and a lug' carried by said inner tubular elementprojecting radially outwardly therefrom into said slot, and means forresiliently restraining radially inward motion of said at lug, wherebythe lug may be displaced radially inwardly against the resilientrestraint thereof to allow relative axial motion of said first andsecond tubular element 7 and whereby said lug, when it projects throughsaid slot, effectively prevents relative axial motion of said first andsecond tubular elements but permits a limited relative rotation thereof.

3. The instrument of claim 1 wherein said means for restraining relativerotation of said elements comprises a plurality of interengaging ribsmounted respectively on the inner surface of said outer tubular memberand on the outer surface of said inner tubular member.

4. The instrument of claim 2 including means on said outer tubularmember cooperating with said lug for providing an indication of therelative angular position of said tubular elements.

5. The instrument of claim 1 including a resilient finger formed in thebody of said inner tubular element and a lug upstanding from saidfinger.

6. The instrument of claim 1 wherein said means for restraining relativemotion of said tubular elements in positions of relative rotationcomprises a first longitudinally extending rib resiliently carried bysaid inner tubular member and projecting radially outwardly therefrom,and a plurality of circumferentially spaced longitudinally extendingribs carried by the outer tubular member and projecting inwardlytherefrom for selective engagement with said first resiliently carriedrib as said tubular elements are relatively rotated.

7. The instrument of claim 1 wherein said inner tubular element includesa spring finger formed therein and having a radially outwardlyprojecting lug and a radially outwardly projecting longitudinallyextending rib formed on said finger, a circumferentially extending slotformed in said outer tubular member for receiving said lug andcooperating therewith to limit relative rotation of said tubularelements, and at least one radially inwardly facing groove formed on theinner surface of said outer tubular member for cooperation with saidoutwardly projecting rib to restrain a relative rotation of said tubularelements.

8. A tool holder comprising an elongated tubular cap having a first toolreceiving bore extending from one end of said cap and centered upon afirst tool axis, an elongated tubular core mounted within said cap forrotation relative to the cap about an operating axis, said core having asecond tool receiving bore extending from one end of the core, saidsecond tool receiving bore being of a diameter substantially equal tothe diameter of said first tool receiving bore and centered upon asecond tool axis,

said first and second tool axes being substantially mutually aligned anddisplaced from said operating axis when said cap and core are in a firstangular position of relative rotation about said operating axis, wherebya tool shank maybe readily inserted and removed from a positionextending within both bores, and whereby relative rotation of said coreand cap to a second angular position will displace one of said tool axesrelative to the other and cause said first and second tool receivingbores to grip said tool shank, and

means for releasably retaining said core and cap in said second angularposition, said cap being formed with an enlarged bore extending fromsaid first tool receiving bore toward the other end of said cap, saidone end of said elongated core being rotatably received in a forwardportion of said enlarged bore of the cap, said core having a rearwardportion ro- 8 tatably received within the enlarged bore of said cap at arear portion thereof to provide a rotatable support for said core withinsaid cap at both the front and rearward ends of said cap and core, saidcap and core being formed of electrically nonconductive material, atleast one of said tool receiving bores being defined by an electricallyconductive sleeve, an electrical conductor connected with saidconductive sleeve and extending rearwardly through said elongated coreand cap, said cap being formed with a circumferentially extending slotand a plurality of circumferentially spaced longitudinally extendingribs adjacent said slot, said ribs extending radially inwardly of saidcap, said elongated core being formed with a spring finger having aradially outwardly projecting lug fixed thereto and extending into saidcircumferentially extending slot of said cap, said finger having alongitudinally extending and radially outwardly projecting rib formedthereon for cooperation with said radially inwardly projecting ribs ofsaid cap to provide a releasable restraint of relative rotation of saidcore and cap.

9. A tool holding chuck comprising a core having a first bore extendinginto the core from one end thereof,

a cap having a second bore extending into the cap from one end thereofand having a diameter substantially equal to the diameter of said firstbore,

means for mounting said cap core for relative rotation about a firstaxis,

said first and second bores being centered upon axes displaced from saidfirst axis and being mutually aligned when said core and cap are in arelease position of relative rotation wherein a tool shank may beloosely engaged within both of said bores,

means for relatively rotating said core and cap toward a grippingposition whereby said bores are relatively radially displaced from eachother and said tool shank is gripped thereby, means independent of saidbores for limiting relative rotation of said core and cap through a pathof limited length whether or not a tool shank is inserted in said chuck,and

means for releasably latching the core and cap in any one of a pluralityof position s of relative rotation within said path, said last namedmeans comprising a plurality of interengaging ribs on said core and cap,at least one of said ribs being resiliently mounted.

10. The chuck of claim 9 wherein said means for relatively rotating saidcore and cap comprises a portion of the cap forming a first handleextending rearwardly from said one end thereof to provide a firstsurface remote from said tool to be grasped by an operator, and furthercomprises a portion of the core forming a second handle extendingrearwardly of said one end thereto to provide a second surface remotefrom said tool to be grasped by an operator, whereby said tool may bereadily gripped or released by operation of said first and secondhandles at a distance from said tool.

11. The apparatus of claim 9 wherein said means for limiting relativerotation of said core and cap comprises a circumferentially extendingslot in one of said core and cap and a lug on the other of said core andcap projecting into said slot.

UNITED STATES PATENT AND TRADEMARK OFFICE CERTIFICATE OF CORRECTIONPATENT NO. 3, 920, 022 DATED November 18, 1975 |NVENTOR(S) acey A.Pastor It rs certified that error appears in the above-identified patentand that said Letters Patent are hereby corrected as shown below:

Col. 4, line 15, extend should be extent C 1, line 64, sonci should besonic 0 C01. 4, line 67, 48 should be 38 C01, line 55, before word innerinsert Word said Signed and Scaled this sixth Day Of April 1976 i [SEAL]I Attest: i

RUTH C. MASON C. MARSHALL DANN Alfsll'ng H ('Hmmissioncr qflatvnls andTrademarks i i F i I i

1. A surgical instrument comprising a rear body portion adapted to be held in the hand of an operator, a forward body portion mounted to said rear body portion for rotation about a first axis and adapted to be grasped and rotated by the fingers of the hand in which the rear body portion is held, said body portions respectively having first and second tool receiving bores positioned at respective forward ends thereof and of substantially equal diameters, each said bore centered upon an axis displaced from said first axis, said bores being aligned with each other when said body portions are in a first release position of relative angular rotation about said first axis, and being relatively misaligned when said body portions are in a second gripping position of relative angular rotation, whereby a tool shank may be freely inserted into or withdrawn fRom said aligned bores when the body portions are in said release position and said tool shank will be firmly grasped by the relatively misaligned bores when the body portions are in said gripping postion, said body portions being readily displaced between said gripping and release positions by a one-handed operation in which said forward body portion may be grasped between the operator''s thumb and another finger and said rear body portion may be grasped between the operator''s palm and other fingers of the same hand to accomplish movement of the body portions between said gripping and release positions, said forward body portion comprising an outer elongated tubular element having said first tool receiving bore formed in a front end thereof and having an enlarged inner bore extending from an inner end of said first tool receiving bore to the rearward end of said tubular element, said rear body portion comprising an inner tubular element having a front end portion rotatably received in a forward portion of said enlarged inner bore of said outer tubular element to provide at least part of the rotatable mounting of said body portions, said tool receiving bore of said rear body portion extending through said front end portion of said inner tubular element in end-to-end relation to the tool receiving bore of said outer tubular element, said inner tubular element including an outer peripheral surface rotatably engaged with an inner surface of the inner bore of said first tubular element at a rear end thereof to provide a part of the rotatable mounting of the two body portions, inner tubular element being axially inserted into said first tubular element and including means for restraining relative rotation of said tubular elements in any one of a plurality of positions of relative rotation.
 2. The instrument of claim 1 wherein said means for limiting relative rotation comprises a circumferentially extending slot formed in said outer tubular element and a lug carried by said inner tubular element projecting radially outwardly therefrom into said slot, and means for resiliently restraining radially inward motion of said lug, whereby the lug may be displaced radially inwardly against the resilient restraint thereof to allow relative axial motion of said first and second tubular element and whereby said lug, when it projects through said slot, effectively prevents relative axial motion of said first and second tubular elements but permits a limited relative rotation thereof.
 3. The instrument of claim 1 wherein said means for restraining relative rotation of said elements comprises a plurality of interengaging ribs mounted respectively on the inner surface of said outer tubular member and on the outer surface of said inner tubular member.
 4. The instrument of claim 2 including means on said outer tubular member cooperating with said lug for providing an indication of the relative angular position of said tubular elements.
 5. The instrument of claim 1 including a resilient finger formed in the body of said inner tubular element and a lug upstanding from said finger.
 6. The instrument of claim 1 wherein said means for restraining relative motion of said tubular elements in positions of relative rotation comprises a first longitudinally extending rib resiliently carried by said inner tubular member and projecting radially outwardly therefrom, and a plurality of circumferentially spaced longitudinally extending ribs carried by the outer tubular member and projecting inwardly therefrom for selective engagement with said first resiliently carried rib as said tubular elements are relatively rotated.
 7. The instrument of claim 1 wherein said inner tubular element includes a spring finger formed therein and having a radially outwardly projecting lug and a radially outwardly projecting longitudinally extending rib formed on said finger, a circumferentially extending slot formed in said outer tubular member for receiving said lug and cooperating therewiTh to limit relative rotation of said tubular elements, and at least one radially inwardly facing groove formed on the inner surface of said outer tubular member for cooperation with said outwardly projecting rib to restrain a relative rotation of said tubular elements.
 8. A tool holder comprising an elongated tubular cap having a first tool receiving bore extending from one end of said cap and centered upon a first tool axis, an elongated tubular core mounted within said cap for rotation relative to the cap about an operating axis, said core having a second tool receiving bore extending from one end of the core, said second tool receiving bore being of a diameter substantially equal to the diameter of said first tool receiving bore and centered upon a second tool axis, said first and second tool axes being substantially mutually aligned and displaced from said operating axis when said cap and core are in a first angular position of relative rotation about said operating axis, whereby a tool shank maybe readily inserted and removed from a position extending within both bores, and whereby relative rotation of said core and cap to a second angular position will displace one of said tool axes relative to the other and cause said first and second tool receiving bores to grip said tool shank, and means for releasably retaining said core and cap in said second angular position, said cap being formed with an enlarged bore extending from said first tool receiving bore toward the other end of said cap, said one end of said elongated core being rotatably received in a forward portion of said enlarged bore of the cap, said core having a rearward portion rotatably received within the enlarged bore of said cap at a rear portion thereof to provide a rotatable support for said core within said cap at both the front and rearward ends of said cap and core, said cap and core being formed of electrically non-conductive material, at least one of said tool receiving bores being defined by an electrically conductive sleeve, an electrical conductor connected with said conductive sleeve and extending rearwardly through said elongated core and cap, said cap being formed with a circumferentially extending slot and a plurality of circumferentially spaced longitudinally extending ribs adjacent said slot, said ribs extending radially inwardly of said cap, said elongated core being formed with a spring finger having a radially outwardly projecting lug fixed thereto and extending into said circumferentially extending slot of said cap, said finger having a longitudinally extending and radially outwardly projecting rib formed thereon for cooperation with said radially inwardly projecting ribs of said cap to provide a releasable restraint of relative rotation of said core and cap.
 9. A tool holding chuck comprising a core having a first bore extending into the core from one end thereof, a cap having a second bore extending into the cap from one end thereof and having a diameter substantially equal to the diameter of said first bore, means for mounting said cap core for relative rotation about a first axis, said first and second bores being centered upon axes displaced from said first axis and being mutually aligned when said core and cap are in a release position of relative rotation wherein a tool shank may be loosely engaged within both of said bores, means for relatively rotating said core and cap toward a gripping position whereby said bores are relatively radially displaced from each other and said tool shank is gripped thereby, means independent of said bores for limiting relative rotation of said core and cap through a path of limited length whether or not a tool shank is inserted in said chuck, and means for releasably latching the core and cap in any one of a plurality of position s of relative rotation within said path, said last named means comprising a plurality of interengaging ribs on said core and cap, at least one of said ribs Being resiliently mounted.
 10. The chuck of claim 9 wherein said means for relatively rotating said core and cap comprises a portion of the cap forming a first handle extending rearwardly from said one end thereof to provide a first surface remote from said tool to be grasped by an operator, and further comprises a portion of the core forming a second handle extending rearwardly of said one end thereto to provide a second surface remote from said tool to be grasped by an operator, whereby said tool may be readily gripped or released by operation of said first and second handles at a distance from said tool.
 11. The apparatus of claim 9 wherein said means for limiting relative rotation of said core and cap comprises a circumferentially extending slot in one of said core and cap and a lug on the other of said core and cap projecting into said slot. 